Graphene is a material of a single-layered lamellar structure composed of carbon atoms. The graphene is almost completely transparent, and only absorbs 2.3% of light; a coefficient of thermal conductivity of the graphene is up to 5,300 W/m·K, which is higher than those of a carbon nanotube and diamond; an electronic mobility of the graphene at room temperature exceeds 15,000 cm2/V·s, which is higher than those of a carbon nanotube or a silicon crystal; an electrical resistivity of the graphene is only 10−8 Ω·m, which is lower than that of copper or silver, that is, the graphene is a material having the smallest electrical resistivity in the world. Due to advantages such as good transparency, small electrical resistivity and fast electron migration rate and the like, the graphene can be used to manufacture transparent touch screens, light panels and solar cells.
Currently, methods for preparing graphene mainly include a mechanical exfoliation method, a chemical vapor deposition method, a pyrolysis epitaxial growth method and so on, wherein the chemical vapor deposition method is simple and easy to prepare the graphene, and can provide large-area graphene with a high quality. For example, a Chinese patent application no. 200810113596.0 discloses a method for preparing graphene by a chemical vapor deposition method, specifically, the method is performed as follows: a substrate provided with catalyst is placed into an oxygen-free reactor to make a temperature of the substrate reach between 500° C.˜1,200° C.; then, carbonaceous matters are added into the reactor, and the graphene is obtained, where the catalyst is a metal or an metallic compound, and the carbonaceous matters are one or more selected from methane, acetylene, ethanol, benzene, toluene and cyclohexane. This process for preparing the graphene provided in the prior art is simple and convenient to operate, and can be used for mass production; moreover, the graphene prepared with this process has relatively good quality. However, the graphene prepared in the prior art has a relatively poor electrical conductivity.